Why do copper wouldn't react with oxygen but coper is coated with a black layer of cupric oxide?
Answers
Note : I think the question should be " Why does copper not react with oxygen in water, but is coated with a black layer of cupric oxide when exposed to atmosphere?"
Reason : Copper does react with oxygen.
Answer:
Copper does not react with oxygen in water, but is coated with a black layer of cupric oxide when exposed to atmosphere. This is because:
1) Copper lies below hydrogen in the reactivity series of metals. Therefore, it cannot displace hydrogen from water and take its place to combine with oxygen. So, it remains unreacted in water.
2) However, copper does react with free oxygen, but slowly. That is why a black layer is formed on the surface of metal copper on coming in contact with air.
3) This is nothing but corrosion of the metal surface. This black coating is of cupric oxide (Cu2O) formed by the reaction of copper with atmospheric oxygen.